Taut band anchor arrangement



June 11, 1968 R. s. MUELLER 3,387,807

TAUT BAND ANCHOR ARRANGEMENT Filed March 14, 1966 INVENTOR.

RICHARD S. MUELLER 3,387,867 TAIUT BAND ANCHOR ARRANGEMENT Richard S. Mueiier, Minnctonka, Mina, assignor to Honeywell Inc, Minneapolis, Minn, a corporation of Delaware Filed Mar. 14, 1966, Ser. No. 534,094 4 Claims. (Cl. 248-17) ABSTRACT OF THE DISCLGSURE A fastening arrangement for a taut band utilized in a taut band suspension type electrical measuring instrument wherein the taut band is held in place at least at one of its extremities between a taut band anchor and a plate which are spotwelded together.

The present invention is directed to a taut band anchor arrangement for incorporation in a taut band suspension mechanism of the type which may be utilized as an electrical measuring instrument.

While taut ban suspension mechanisms have distinct inherent advantages over pivot and jewel mechanisms, a number of problems can be encountered which if not alleviated can aitect the accuracy of the taut band suspension mechanism and thereby detract from such advantages. Thus unless the taut bands are positively positioned with respect to the respective taut band anchors, shifting of the taut bands with respect to the taut band anchors may arise due to shocks and vibrations experienced in use which may cause a change in the operating characteristics of the mechanism. Further, when taut hands are fastened to taut band anchors by soldering or similar heat fastening processes, hysteresis in the mechanism, brittleness of the taut bands, and changes in resilience of those taut band anchors formed of resilient material may be encountered. Thus the flux used in the soldering process may find its way to the active portion of the taut bands from which it may prove quite difiicult to remove thereby resulting in hysteresis to be experienced. Also, the relative prolonged and extensive heat utilized in the soldering process may impart brittleness to the taut bands and even change the resilience of those taut band anchors which are formed of spring material.

With the present invention, the problems of taut bands shifting with respect to an associated taut band anchor and hysteresis of a taut band suspension mechanism caused by flux deposition on the taut bands. brittleness of the taut bands, and loss of resilience of resilient taut band anchors caused by the heat of fastening the taut bands to the taut band anchors are not encountered. This is because the taut bands are associated with the taut band anchors by means of a sandwich configuration in that a plate is disposed over and is contiguous with the taut band and the taut band anchor, the taut band being located between the taut band anchor and the plate. The plate is spotwelded to the taut band anchor resulting in a rigid assembly of the taut band anchor, taut band, and plate. The taut hand thus becomes a prisoner between the taut band anchor and the plate and is limited against shifting with respect to the taut band anchor. Further, since the taut hand is a prisoner between the taut band anchor and the plate, any brittleness which might be encountered because of the spotweld is localized to a small portion of the taut band and that portion is located within the sandwich and as a practical matter is so isolated that such brittleness does not have any adverse effect. Also, since the heat of the spotweld is localized, the possibility of the resilience of the resilient taut band anchors being affected is minimized. Of course since soldering is not States Patent 3,387,8h7 Patented June 11, 1968 utilized to fasten the taut bands to the taut band anchors, flux is not deposited on the active portions of the taut bands and hence the hysteresis problem caused by fiux deposition is completely bypassed.

Therefore, it is an object of the present invention to provide a taut band anchor arrangement wherein shifting of the taut band with respect to the taut band anchor is positively limited by the construction of the arrangement.

Another object of the present invention is to provide a taut band anchor arrangement wherein heat fastening of the taut band to the taut band anchor does not give rise to any brittleness in the taut band which adversely effects the remainder of the arrangement.

A further object of the present invention is to provide a taut band anchor arrangement wherein the change in the resilience of the resilient taut band anchors caused by heat fastening the taut bands thereto is minimal.

These and other objects will become more apparent from a reading of the following specification and claims taken in conjunction with the drawing in which:

FIGURE 1 is an assembly in partial cross section of an electrical measuring instrument of the moving coil type including a taut band suspension mechanism incorporating the invention;

FIGURE 2 is an enlarged view of the upper section of the taut band suspension of FIGURE 1 including the rigid taut band anchor associated with the moving coil and the resilient taut band anchor associated with the stat onary structure of the instrument;

FIGURE 3 is a perspective explosion view of the rigid taut band anchor of FIGURE 2;

FIGURE 3A is a perspective view of the rigid taut band anchor of FIGURE 2; and

FIGURE 4 is a perspective explosion view of the resilient taut band anchor of FIGURE 2.

Referring to FIGURE 1, an electrical measuring instrument including a taut band suspension mechanism is shown. A ferrous metal yoke member 10 supports a subassembly comprised of a pair of identical U-shaped upper and lower frame members 12 and 13, respectively, which in turn support 'a magnet core member 14 about which a moving coil 16 is disposed. The coil 1-6 is supported by and arranged for rotative oscillatory movement about upper and lower taut bands 18 and 19, respectively. The taut bands 18 and I? which may be of platinuml nickel composition extend between rigid upper and lower taut band anchors 2i) and 22, respectively, appropriately supported from the coil 16 and identical upper and lower resilient taut band anchors 24 and 26, respectively, supported from the frame members 12 and 13, respectively, by resilient grommets 28 which are snap fastened into openings 12a and 13a, respectively, thereof. The foregoing description of the electrical measuring instrument of FIGURE 1 is believed adequate for the purposes of the present invention. However, if a more complete description is desired, attention is drawn to the Donald A. Mothes application, Ser. No. 533,139, filed Mar. 10, 1966, assigned to the assignee hereof.

The upper section of the taut band suspension of FIG- URE 1 comprised of rigid taut band anchor 20, taut band 18, and resilient taut band anchor 24 is shown in FIG- URE 2. The reference to the upper section of the taut band suspension will be made throughout although it should be recognized that the lower section of the taut band suspension comprised of rigid taut band anchor 22, taut band 19, and resilient taut band anchor 26 is identical except for the particular form of the taut band anchor 22. Again, for the particular form of this anchor, reference can be made to the forementioned Mothes application.

Referring now to FIGURE 2, the rigid taut band anchor 20 consists of generally flat member 2%! formed of brass and plate member 20b formed of Phosphor bronze and the resilient taut band anchor 24 consists of generally U-shaped member 24a formed of beryllium copper and plate member 24!) for-med of Phosphor bronze. Taut band 18 which extends between the rigid taut band anchor 20 and resilient taut band anchor 24 has one extremity 18a disposed between fiat member 29a and plate member 20b and the other extremity 18!) disposed between U-shaped member 24a and plate member 2412. The plate members 20b and 24b which overlie and are contiguous with the fiat member 20a and the U-shaped member 24b, respectively, are fastened thereto by a spotweld which is applied to the plates and which extends therethrough to the flat member and the U-shaped member, respectively. This fastening results in rigid taut band anchor 20 and resilient taut band anchor 24 including a sandwich portion comprised of flat member 20a, taut band extremity 18a, and plate 201) and U-shaped member 2411, taut band extremity 18b, and flat member 2411, respectively, whereby the extremities of the taut band are made prisoners between the elements.

The relationship between the taut band 18 and the rigid taut band anchor 20 and resilient taut band anchor 24 is shown in further detail in FIGURES 3 and 4, respectively.

With the rigid taut band anchor 20, as shown in FIG- URE 3, the taut band 18 is arranged to extend through opening 200 of fiat member 20a and engage side wall 20d (refer also to FIGURE 2). The taut band extremity 18a is arranged to be located at 90. to the taut band 18 on the smooth regular surface 20;: of the flat member substantially along the medial longitudinal axis thereof. The plate member 20b is arranged to overlie the taut band extremity 18a and be contiguous therewith and with the flat member 20a as was indicated previously. The spotweld which is applied to the plate member 2% and extends therethrough to the flat member 200: is placed quite close to the curvature which initiates the opening 200 so as to more positively position the taut band 18 and limit it against shifting. The spotweld may be provided as identified by the X in FIGURE 3A so that it extends through the taut band extremity 18a, thereby guaranteeing that the taut band extremity is fixed to the fiat member 20a and plate member 20b rather than merely relying on the prisoner effect provided by the taut band extremity being disposed between the spotwelded together flat member and plate member. In any event, because the taut band 18a is disposed between the fiat member 20a and the plate member 20b and the spotweld applied to the resulting assembly, the effect of any brittleness which might be encountered in the taut band extremity 18a because of the heat of the spotweld is minimized.

The U-shaped member 24:: of the resilient taut band anchor 24 is initially formed in the shape shown in FIG- URE 4 and includes an opening 24c in the base portion 24d thereof through which taut band 18 is disposed. Extremity 18b of the taut band 18 is arranged to engage the curved surface 24a (refer also to FIGURE 2) provided between the legs 24 of the cantilever portion 24g of the U'shaped member 24a and is further arranged to be located at 90 to the taut band 18 on the smooth regular surface 24h of the free end of the cantilever portion and substantially along the medial longitudinal axis thereof. The plate member 24b is arranged to be associated and fastened to the taut band extremity 18b and U-shaped member 24a in the same manner as set forth above with respect to the rigid taut band anchor 20 of FIGURE 3. It will be appreciated that because of the localized heat and short duration thereof involved in providing the spotweld the change of resilience of the U-shaped member 24a is minimized.

In assembling the taut band suspension, referring again to FIGURE 1, upper and lower rigid taut band anchors 20 and 22, respectively, are first fabricated and appro- 4 priately secured to the coil 16, for example, as set forth in-the forementioned Mothes application. Ther-eupon, with the coil disposed about the core member 14, frame members 12 and 13 with the upper and lower resilient taut band anchors 24 and 26, respectively, in place are asso: ciated with the core member. The taut bands 18 and 19 which are of sufiicient length are then threaded through the openings in the grommets 28 and associated with the resilient taut band anchors 24 and 26, respectively, so as to allow the spotweld fastening to take place.

It will be noted that the form of the U-shaped member 24a of the resilient taut band anchor 24 in FIGURE 4 is of slightly different form when compared to that in FIGURE 2 which of course would also be the case with respect to resilient taut band anchor 26. This is because in securing the taut bands to the U-shaped members and to provide the necessary tension in the taut bands, the cantilever portions of the U-shaped members are each moved inwardly followed by the drawing of the respective taut band across the curved surface so as to make it taut and to provide the proper tension thereto. Following the proper tension being applied to the taut bands, the respective plate member is overlaid the taut band and the U-shaped member and is spotwelded in place.

The taut band anchor arrangement just set forth not only allows for the elimination of hysteresis problems caused by flux deposition on the active portions of the taut bands since no flux is utilized, but also positively limits the shifting of the taut bands with respect to the taut band anchors. Further, because of the application of the spotweld in an area Where the taut bands are prisoners, the effect of any brittleness which might be imparted to the taut hands by the heat of the spotweld is minimized. Also because of the localized heat of the spotweld, any change in the resilience of the resilient taut band anchors is kept to a minimum.

Various modifications can be made to the invention and, therefore, the scope of the invention should be deter mined from the following claims.

What is claimed is:

1. A taut band suspension type electrical measuring instrument comprising: a fixed element; a moving element; and a taut band disposed between said elements and connected thereto; and a taut band anchor arrangement connecting said taut band and one of said elements including a taut band anchor having a smooth regular surface; said taut band disposed on and extending beyond said surface, and a plate conforming to and overlying said smooth regular surface and said taut band and contiguous therewith; said taut band anchor, said taut band, and said plate forming a single sandwich assembly by means of a spotweld extending between said plate and said taut band anchor.

2. The arrangement of claim 1: wherein the smooth regular surface of said taut band anchor and the conforming surface of said plate are fiat..

3. The arrangement of claim 2: wherein the spotweld is in line with said taut band.

4. The arrangement of claim 1: wherein the taut band is guided by a smooth regular surface of said taut band anchor at substantially to the first mentioned surface wherein said surfaces are connected and of smooth curvature; and wherein the spotweld is adjacent the termination of the curvature.

References Cited UNITED STATES PATENTS 656,125 8/1900 Kleinscllmidth 287-20.2 1,339,703 5/1920 Green 248-493 1,651,351 11/1927 Rumely 248-119 2,113,134 4/1938 Godfrey 248328 2,548,993 4/1951 Mierziva 2481l9 X JOHN PETO, Primary Examiner. 

